Right? Why do you so @exts{@exts} and not %exts{@exts}?

A slice acts as an array. So therefore, the starting symbol is "at", meaning "array".

-- Randal L. Schwartz, Perl hacker

Slices don't act like arrays in scalar context though.

That has always bugged me. Personally I wish that Perl were a little less DWIM about:

$elem = @array[0];
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If that did something completely unexpected to the novice, then they might learn sooner what the correct notation is...

No, they act like lists in a scalar context, to be precisely equal to their definition in perldata.

-- Randal L. Schwartz, Perl hacker

Sorry to keep bugging y'all, but this is really helpful and interesting. So if I did something like this:

@exts{@exts} = @exts;
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would that make both the keys AND the values equal (and obviously, the values of the @exts array)?

Yes. See:

    my @exts = qw/foo bar baz/;
    my %exts;

    @exts{@exts} = @exts;

    use Data::Dumper;
    print Dumper \%exts;
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produces:

    $VAR1 = {
          'foo' => 'foo',
          'baz' => 'baz',
          'bar' => 'bar'
        };
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I might point out that nothing answers a question so well as testing a bit of code out yourself. :)